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Post by cobbledstones on Oct 25, 2015 21:49:41 GMT -5
I picked up a Covington marble/bead mill on craiglist a little while ago, but have yet to use it. Thought that should change, so I started a batch.
the machine can make 20+ marbles at a time. It seems like the most work happens on the preforming. I timed my progress to find out.
drop saw was best for chunking up rocks into marble sized pieces. made 80 blanks in an hour, and picked out 23. 
an hour and 40 minutes later, I had the cylinders roughed out 
another 35 minutes and it was time for dinner, have to wait till next weekend to finish the rough out 
all done freehand thus far, it took a couple tries to get ones that were reasonably round.
thanks for looking,
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Post by paulshiroma on Oct 26, 2015 7:53:10 GMT -5
Nice score on Craigslist. And nice job on the marbles.
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Post by captbob on Oct 26, 2015 12:35:08 GMT -5
Never paid attention to a bead mill before, but that's kinda cool. How about a picture of the machine?
How did you turn the pieces in picture 1 into picture 2?
They go in the bead mill as shaped in pic 2? How big can you make them?
Do you use grits and polish like tumbling? They get as shiny as a good tumbled rock just in the mill?
Looking forward to seeing finished marbles!
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Post by cobbledstones on Oct 26, 2015 13:29:44 GMT -5
Never paid attention to a bead mill before, but that's kinda cool. How about a picture of the machine? How did you turn the pieces in picture 1 into picture 2? They go in the bead mill as shaped in pic 2? How big can you make them? Do you use grits and polish like tumbling? They get as shiny as a good tumbled rock just in the mill? Looking forward to seeing finished marbles! , I will take a pic of the machine to post, but it is this thing1-->2 is accomplished on the supergrinder, just a stacked set of saw blades. Look close and you can see the corduroy edges because I put spaces between the blades. This thing eats rock like butter, gotta wear safety equipment, little shards of rock go flying. 2--> 3 is also freehand on the grinder, those are the preforms that will go into the machine you have to make enough preforms to just about fill the machine so it works right (or so I have read). The biggest you can do is around 1/2" which is what I am shooting for with my preforms. At this size, that means about 20 preforms. According to the instructions, you use tumbler grit (80) in the machine, and that makes the near marbles into marbles. From there you can progress through grits or throw them in a vibe tumbler to finish (must do polish in tumbler). I plan to do the 80 grit stage in the mill, then toss into my next UV10 batch. This is all an experiment for me, will show the face-plant or success as it unfolds |
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Post by captbob on Oct 26, 2015 13:45:31 GMT -5
Thank you for the explanation. That just looks like fun.
Now that you linked the machine, (I also went and found a Utube video) I'd like see your supergrinder!
You made those little balls with your grinder?! Got all your fingers still?
I MUST make one of those (supergrinder) sooner rather than later.
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Post by broseph82 on Oct 26, 2015 14:22:27 GMT -5
It looks as if you dont even need this bead mill cobbledstones! Great job on the preforming. So is this thing in essence a tumbler? You pretty much make the marble by hand and then it does the final touch and polish? |
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Post by cobbledstones on Oct 26, 2015 15:37:18 GMT -5
It looks as if you dont even need this bead mill cobbledstones! Great job on the preforming. So is this thing in essence a tumbler? You pretty much make the marble by hand and then it does the final touch and polish? It is supposed to bring them even closer to round, time will tell |
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Post by cobbledstones on Oct 26, 2015 15:42:22 GMT -5
captbob fingers intact, even after using this beast. It is my absolute favorite tool. Have since added a a back-splash made out of roofing flashing. I sit on a stool in front of a clean trash can, apron on such that most of the water and debris goes into the can. There is something really enjoyable about pulverizing rock in no time. 
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Post by paulshiroma on Oct 26, 2015 23:02:04 GMT -5
Never paid attention to a bead mill before, but that's kinda cool. How about a picture of the machine? How did you turn the pieces in picture 1 into picture 2? They go in the bead mill as shaped in pic 2? How big can you make them? Do you use grits and polish like tumbling? They get as shiny as a good tumbled rock just in the mill? Looking forward to seeing finished marbles! x2 on this. I went and looked it up after reading your post. Very cool. |
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Post by captbob on Oct 27, 2015 1:28:37 GMT -5
I like the way you mounted your super grinder! That's thinkin' right there.
smart smart smart!!
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Post by cobbledstones on Oct 27, 2015 9:36:29 GMT -5
Thanks captbob, I have all my Polys (4) wall mounted on a false wall with motors above. Can't take credit for the thinking, I read about it either here or another rock forum (can't seem to find the link now) The false wall gives a little chase to keep electricity behind and the water in front. What I like the best is that I can grind really large items, and the whole set of grinders doesn't take up much space. |
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Post by captbob on Oct 27, 2015 10:14:13 GMT -5
I have all my Polys (4) wall mounted on a false wall with motors above. okay cobbledstones, I don't want to invade your privacy, but I would really like to see this wall of Polys. I think I can picture your false wall with the motors above, but actually seeing what you have built would sure be better than my trying to imagine it. Anyway, would love to see it (your wall & set up) if you care to share. And... who doesn't have a MFR box from Mel sitting on their shop floor?!  |
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Post by cobbledstones on Oct 27, 2015 11:38:54 GMT -5
no invasion, I'll take a pic tonight and put it up. Notice that the box from Mel is empty. Those got cut quick. |
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Post by cobbledstones on Oct 27, 2015 19:25:23 GMT -5
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Post by captbob on Oct 27, 2015 20:29:32 GMT -5
 I've seen some pretty cool set ups here, but I absolutely love this! Simple in concept, yet creative and perfectly designed for it's intended purpose. Thank you for posting the picture. I'm completely awed.  |
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Post by cobbledstones on Oct 27, 2015 22:18:13 GMT -5
aww shucks, thank you. I have one more poly, but am out of wall space.
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Post by captbob on Oct 28, 2015 9:41:43 GMT -5
I do have one more question for you, hope you don't mind. Maybe others have an opinion as well... On your super grinder, does it matter that there is so much more weight on one end of the arbor than what is on the other end? Did you do (add) anything to balance the ends or does it seem to make a difference at all? I was going to use an old Lortone unit that I have just sitting around unused for the past 10 years to make my super grinder.  But I like your Poly arbor idea in that it removes the waste rock and water from the machine, therefore requiring minimal clean up. Got a couple of those Poly arbors somewhere around here, so it's just a matter of MacGyvering a portable stand. I want to be able to wheel it outside to use. You have about 10 saw blades bunched on the grinder end? okay... that was more than one question  |
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Post by cobbledstones on Oct 28, 2015 10:13:16 GMT -5
I didn't do anything for the left-right balance (roll torque) and I haven't seen any issues (built it a year ago). A 3/4" steel shaft can support a lot of weight so long as the arbor unit itself is secure. In the long tern, the bearing on the heavy side may wear faster, but that is just a guess. I thought I would use the single blade on the left a lot. I was wrong. Going to swap it out for something more useful, just haven't thought through all of the alternatives yet. yep 10 blades, with an old CD between each. I just did the calculation of kerf + CD thickness to get around 1.5" wide. Cheap 9" blades had a really wide kerf that got me there, but I was lucky because I had the 10" poly hoods on hand. If you use smaller blades, you may need to buy more for the same width. Bought my blades here. Don't know if they are still the cheapest, but they treated me right. The blades I ordered were out of stock so they send the next most expensive for same price. The supergrinder is going to be the baby in the shop once I have built grindzilla. A couple years ago I picked up a 20" diameter scintered diamond grinding wheel (5/8" deep scintering! looks like 60 grit) from a surplus sale at a military aviation manufacturer. Has an 8" hub of some sort for mounting. Thing weighs about 90 lbs. |
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Post by paulshiroma on Oct 28, 2015 21:49:28 GMT -5
Very, very impressive grinding wall...I like it.
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Post by captbob on Oct 29, 2015 10:07:51 GMT -5
Did you go with the 9" blades from that link? $11.15 each? Just curious, but what is the shaft size on these Poly arbors? Also ... grindzilla ?!!  Must see picture of that wheel  8" hub? gonna be an interesting build for sure! ETA: Sorry to keep taking your thread off topic. |
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8" hub? gonna be an interesting build for sure!
